U.S. Pat. No. 4,841,998 to Bruya is directed to a method of decontaminating soil by removing organic hazardous waste with an aqueous ammonia solution. In this process, contaminated soil is introduced to a screen whereby undersized particles are passed to a hopper. Oversized particles are moved to a crusher and then reintroduced to the screen. Once passing to the hopper, the soil is next placed in an agitator whereby an aqueous ammonia solution is introduced. The chemical reaction between the ammonia solution and the contaminants causes the contaminates to adhere to the ammonia. The resulting solution-contaminant mix and soil are then placed in a settling tank. Separation is achieved in the settling tank wherein the solution-contaminant mix is removed from the heavier soil. Further separation of fine soil particles from contamination is achieved in a centrifuge. Separation in this invention is therefore achieved through chemical reaction and not through differentials in specific gravity. This process is intended for removing organic hazardous waste and does not disclose any teaching of removing asbestos or other solid contaminants.
U.S. Pat. No. 4,815,668 to Frei discloses a process for recovering fibrous and/or granulated material from household and industrial waste. This is accomplished by preliminary comminution, magnetic separation, classification, drying and fractionation, wherein the light fraction resulting from the classification carried out after the magnetic separation is subjected to secondary comminution by cutting. The heavy fraction is subject to predominately granulating secondary comminution. Both comminution products are recombined and then fractionated into fibrous and granulated matter. There is no suggestion that this process can accommodate medium such as soil nor can such process result in separation of material such as asbestos.
U.S. Pat. No. 4,699,721 to Meenan et al. discloses a process and apparatus for removing organic contaminates from fluidizable solid material. Such contaminates are removed by boiling and then capturing the separated condensate. Since asbestos and some other solid contaminates are not readily vaporizable, this reference does not suggest treatment of such contaminates.
U.S. Pat. No. 4,820,315 to DeMarco is directed to removing particulate asbestos matter from a fluid such as air and from surfaces through use of a vacuum device. There is no teaching that indicates particulate matter separation is achieved through a process of mixing and settling.
U.S. Pat. No. 5,055,196 to Darian et al. discloses a method of decontaminating material such as soil or sludge whereby inorganic or organic contaminants are removed. The targeted contaminants are primarily ones such as PCBs and other organics. This is accomplished by contacting a water-wet solid mixture with a solvent containing a comminuting surfactant. The solvent used is a solvent for the contaminant and is sparingly soluble in water. The purpose of adding the comminuting surfactant to the solvent is to form a dispersed mixture of the solids, contaminants, and water whereby the contaminants are extractable into the solvent. The solvent-contaminant mix is separated from the soil and ultimately, the contaminant is removed from the solvent mix. Thus, separation is achieved through the natural affinity between the solvent and contaminates.
While each of the inventions described above fulfills its intended purpose, none of them are directed towards decontamination of soil, particularly from asbestos, in the manner as disclosed in this invention.